Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 1 | // Copyright 2014 the V8 project authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
| 4 | |
| 5 | #include "src/compiler/load-elimination.h" |
| 6 | |
Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 7 | #include "src/compiler/graph.h" |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 8 | #include "src/compiler/node-properties.h" |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 9 | #include "src/compiler/simplified-operator.h" |
Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 10 | #include "src/types.h" |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 11 | |
| 12 | namespace v8 { |
| 13 | namespace internal { |
| 14 | namespace compiler { |
| 15 | |
| 16 | LoadElimination::~LoadElimination() {} |
| 17 | |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 18 | Reduction LoadElimination::Reduce(Node* node) { |
| 19 | switch (node->opcode()) { |
| 20 | case IrOpcode::kLoadField: |
| 21 | return ReduceLoadField(node); |
| 22 | default: |
| 23 | break; |
| 24 | } |
| 25 | return NoChange(); |
| 26 | } |
| 27 | |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 28 | Reduction LoadElimination::ReduceLoadField(Node* node) { |
| 29 | DCHECK_EQ(IrOpcode::kLoadField, node->opcode()); |
| 30 | FieldAccess const access = FieldAccessOf(node->op()); |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 31 | Node* object = NodeProperties::GetValueInput(node, 0); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 32 | for (Node* effect = NodeProperties::GetEffectInput(node);; |
| 33 | effect = NodeProperties::GetEffectInput(effect)) { |
| 34 | switch (effect->opcode()) { |
| 35 | case IrOpcode::kLoadField: { |
Ben Murdoch | c561043 | 2016-08-08 18:44:38 +0100 | [diff] [blame] | 36 | FieldAccess const effect_access = FieldAccessOf(effect->op()); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 37 | if (object == NodeProperties::GetValueInput(effect, 0) && |
Ben Murdoch | c561043 | 2016-08-08 18:44:38 +0100 | [diff] [blame] | 38 | access == effect_access && effect_access.type->Is(access.type)) { |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 39 | Node* const value = effect; |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 40 | ReplaceWithValue(node, value); |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 41 | return Replace(value); |
| 42 | } |
| 43 | break; |
| 44 | } |
| 45 | case IrOpcode::kStoreField: { |
| 46 | if (access == FieldAccessOf(effect->op())) { |
| 47 | if (object == NodeProperties::GetValueInput(effect, 0)) { |
| 48 | Node* const value = NodeProperties::GetValueInput(effect, 1); |
Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 49 | Type* stored_value_type = NodeProperties::GetType(value); |
| 50 | Type* load_type = NodeProperties::GetType(node); |
| 51 | // Make sure the replacement's type is a subtype of the node's |
| 52 | // type. Otherwise we could confuse optimizations that were |
| 53 | // based on the original type. |
| 54 | if (stored_value_type->Is(load_type)) { |
| 55 | ReplaceWithValue(node, value); |
| 56 | return Replace(value); |
| 57 | } else { |
| 58 | Node* renamed = graph()->NewNode( |
Ben Murdoch | c561043 | 2016-08-08 18:44:38 +0100 | [diff] [blame] | 59 | simplified()->TypeGuard(Type::Intersect( |
| 60 | stored_value_type, load_type, graph()->zone())), |
Ben Murdoch | da12d29 | 2016-06-02 14:46:10 +0100 | [diff] [blame] | 61 | value, NodeProperties::GetControlInput(node)); |
| 62 | ReplaceWithValue(node, renamed); |
| 63 | return Replace(renamed); |
| 64 | } |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 65 | } |
| 66 | // TODO(turbofan): Alias analysis to the rescue? |
| 67 | return NoChange(); |
| 68 | } |
| 69 | break; |
| 70 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 71 | case IrOpcode::kBeginRegion: |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 72 | case IrOpcode::kStoreBuffer: |
| 73 | case IrOpcode::kStoreElement: { |
| 74 | // These can never interfere with field loads. |
| 75 | break; |
| 76 | } |
Ben Murdoch | 4a90d5f | 2016-03-22 12:00:34 +0000 | [diff] [blame] | 77 | case IrOpcode::kFinishRegion: { |
| 78 | // "Look through" FinishRegion nodes to make LoadElimination capable |
| 79 | // of looking into atomic regions. |
| 80 | if (object == effect) object = NodeProperties::GetValueInput(effect, 0); |
| 81 | break; |
| 82 | } |
| 83 | case IrOpcode::kAllocate: { |
| 84 | // Allocations don't interfere with field loads. In case we see the |
| 85 | // actual allocation for the {object} we can abort. |
| 86 | if (object == effect) return NoChange(); |
| 87 | break; |
| 88 | } |
Emily Bernier | d0a1eb7 | 2015-03-24 16:35:39 -0400 | [diff] [blame] | 89 | default: { |
| 90 | if (!effect->op()->HasProperty(Operator::kNoWrite) || |
| 91 | effect->op()->EffectInputCount() != 1) { |
| 92 | return NoChange(); |
| 93 | } |
| 94 | break; |
| 95 | } |
| 96 | } |
| 97 | } |
| 98 | UNREACHABLE(); |
| 99 | return NoChange(); |
| 100 | } |
| 101 | |
| 102 | } // namespace compiler |
| 103 | } // namespace internal |
| 104 | } // namespace v8 |